I think Mies van der Rohe is a little bit of a blowhard. Look how he faked the "structural" steel in the Seagram Building. It is as much a decoration as a marble facade.

Mies would have wanted the steel frame to be visible to all; however, American building codes required that all structural steel be covered in a fireproof material (steel, with its low melting point, will fail in fires), usually concrete. This hid the structure of the building – something Mies wanted at all costs to avoid – so Mies used non-structural bronze-toned I-beams to suggest structure instead. These are visible from the outside of the building, and run vertically like mullions in the large glass windows. Now, observers look up and see a fake structure tinted bronze covering a real steel structure.

http://www.newyork-visit.com/new-york-seagram-building/